Fix/stderr

[dsilhavy]

This is supposed to address #613

• stderr.txt is copied to the Representation subdirectories
• HEALTH module does no longer include MPD duration checks which causes test interruption if failing
• Output of stderr.txt is stored in the resulting JSON as a new entry:

SEGMENT_VALIDATION": {
      "": {
        "test": [
          {
            "spec": "Segment Validation",
            "section": "Segment Validation",
            "test": "std error output",
            "messages": [
              "..\/src\/ValidateAtoms.cpp : 3999 : colr atom of type nclx found, the software does not handle colr atoms of this type. \n..\/src\/ValidateAtomList.cpp : 2339 : WARNING: In moov-1:udta-1 - unknown\/unexpected atom 'meta'\nAccording to DASH-IF IOP Section 3.2.8 @bandwidth of the Representation (300000 bps) is set too high given the @minimumBufferTime (2 s), the minimum @bandwidth value required to conform is 296978 bps.\n"
            ],
            "state": "FAIL"
          }
        ],
        "verdict": "FAIL"
      },
      "verdict": "FAIL"
    }

[Phencys]

I have changed the logic for the error messages a bit, as not every line of output has to emit a FAIL level message on the stream.